The Experimental Research Of Upgrading And Reconstruction Of Seweage Treatment Plant Applying Flocculation+Long Fiber Filter

Based on the research of effluent water quality of the second pond in sewage treatment plant, the test of the second pond water which was used as raw water was carried out by Flocculation+long fiber filtration, the static and dynamic coagulation effect of different coagulants and aid coagulant was studied, the effect and feasibility of the flocculation+long fiber filtering technology applied for upgrading and reconstruction of seweage treatment plant was systematicly analyzed.The analysis of the water quality of the second pond in sewage treatment plant showedthat SS in effluent water was 6.96-10.44mg/L,turbidity was 6～9NTU,TP was 0.72～1.15mg/L,TN was 12.32-14.56mg/L,CODcr was 20.15-42.16mg/L. The dissolved state of TP accounted for 92.88%, the suspended state accounted for 7.12%; The dissolved state of CODcr accounted for 91.89%, the suspended state accounted for 8.11%; The dissolved state of TN accounted for 95.26%, the suspended state accounted for 4.74%. Thereinto the NO3-N accounted for 83.32%, NO2-N accounted for 1.32%, NH3-N accounted for 7.98%, organic nitrogen accounted for 7.38%.AS、PAC、PFS was choosed as coagulants. Through static coagulation experiment test, PAC was selected as the best coagulant dealed with the second pond water, the best dosage was 80mg/L; After adding the aid coagulant PAM, PAC+PAM was determined as the best drug combination, dosage respectively is 80mg/L、 3.5mg/L. Pollutants removal effect in static coagulation experiment indicates that adding PAC alonely can effectively remove turbidity and TP, the removal rate can reach over 60%, the removal rate of TN and NH3-N is 7.53%、8.31%, the removal rate of CODcr can reach 25.65%. The mixed addition of PAC and PAM accelerated particles flocculation speed; The removal rate of turbidity reached more than 60%, the improvement of removal rate of TP compared with adding PAC alonely was not obvious, the removal rate of TN、CODcr was 11.42%、24.75%.Three different kinds of filtering model:the long fiber filter; addition of PAC flocculation+long fiber filter; additon of PAC+PAM flocculation+long fiber filtration was studied. The direct filtration test results show that long-fiber filter under various initial filtration rate of 20m/h～50m/h can reduce turbidity under 0.5NTU in 1 minute or less, the longer the filtering period was, the more qunatities of saved dirt was (the qunatities of saved dirt can reach 6 to 10kg/m3), the removal effect of turbidity was remarkable, the average removal rate can reach more than 60%. The removal rate of TP、TN、CODcr was not high, just removing a small amount of suspended state, the removal rate were 12.54%、12.54%、0.14%; When the suspended solids and state carbon, nitrogen and phosphorus of effluent water in sewage treatment plant,and TP、TN、CODcr in raw water can meet the first level A criteria, the applying of long fiber filter for upgrading and reconstruction of seweage treatment plant was recommended. The results of PAC flocculation+long fiber filter test showed that initial filter speed between 20 to 50 m/h, PAC coagulation dynamic optimal dosage is 60mg/L; the removal rate of turbidity and TP reached over 70%, the removal rate of TN、CODcr was 10.32%、16.21%, the infiltration in the effective filtration cycle can meet the first level A criteria;When suspended solids and carbon and nitrogen,TP in particle state in the sewage treatment plant, and TN、CODcr in raw water can meet the first level A criteria, PAC flocculation+long fiber filter applied for upgrading and reconstruction of seweage treatment plant was recommended. The results of the PAC+PAM flocculation+long fiber filter test showed that when the initial filter speed was between 20 to 50 m/h, the best dynamic composite dosage of PAC+PAM was respectively 60mg/L.6mg/L; When the TP of raw water was about lmg/L, the removal effect of TP by adding PAM was very obvious. Three hours before the beginning of filtering, TP in effluent water basically maintain below 0.2mg/L, TP in effective filtration cycle are less than 0.5mg/L. At the beginning, flocculation filter time is short, when the initial filtration rate was between 20m/h-50m/h, turbidity can be reduced under 0.5NTU within two minutes or less, filter material quantity was high (16 to 34kg/m3); The removal rate of TN. CODcr were 9.91%、14.65%, the effluent water can meet the first level A criteria. When suspended solids, carbon and nitrogen and TP in partical state is high in the sewage treatment plant, TN. CODcr in raw water can meet the first level A criteria, PAC+PAM flocculation+long fiber filter applied for upgrading and reconstruction of seweage treatment plant was recommended.The results applying zeolite for the removal of TN showed that using the natural clinoptilolite of 60～80 mesh, the adsorption equilibrium time was 90 min, optimal dosage of adsorbent was 30g/L, the removal rate of TN、NO3-N is less than 10%, and the removal rate of NH3-N was as high as 90%. For TN in the effluent water of second pond were mainly composed of nitrate nitrogen in the wastewater treatment and the applying of zeolite of the enhanced remocal of TN were not a suitable choose.